Microbiology of Traditional Meat Products of Sikkim and Kumaun Himalaya
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Microbiology of Traditional Meat Products of Sikkim and Kumaun Himalaya Thesis Submitted for the Degree of Doctor of Philosophy in Science (Botany) of the Kumaun University 2008 ARUN KUMAR RAI Food Microbiology Laboratory Department of Botany Sikkim Government College Tadong 737 102, Sikkim & Department of Botany D.S.B. campus, Kumaun University Nainital 263 002, Uttarakhand 65 Microorganisms transform the chemical constituents of raw substrates during fermentation into acceptable food products with improved flavour, aroma and texture, enhancing nutritional value and other health benefits (Steinkraus, 1996; Stiles and Holzapfel, 1997; Tamang, 2007). Microorganisms are mostly present in or on the raw materials, ingredients, utensils, environment, and are selected through adaptation to the substrate for fermentation (Hesseltine, 1983; Tamang, 1998). Any animal can be used as a source of meat, ranging from domesticated cow, pig and chicken, to deer and camels, and it is a good source of easily digestible protein and contains essential amino acids which are vital for growth and maintenance of the body (Fellows and Hampton, 1992). Raw meat gets spoiled at high ambient temperatures within a few hours due to its high moisture and protein contents (Dzudie et al., 2003). Fermentation or drying or smoking prolongs the shelf-life of perishable raw meat (Rantsiou and Cocolin, 2006). Traditional cured meat products, made from whole meat pieces of pork or beef, are commonly produced and consumed in different countries throughout the world (Vilar et al., 2000). In developed countries, a wet-curing process for meat has been evolved which involves use of a solution of salt, sodium nitrate/nitrite, whereas in under-developed and developing countries, preserving meat is done by curing with salt followed by drying or smoking or fermentation (Zapata et al., 1990; Romano et al., 2006). 66 Fermented meat products are divided into two categories: those made from whole meat pieces or slices, such as dried meat and jerky, and those made by chopping or comminuting the meat, usually called sausages (Campbell-Platt, 1987). Meat processing is the combination of chemical curing, microbial fermentation and drying which together give stable, safe, ready-to-eat products (Bacus, 1984). Pederson (1980) gave an account of the history of meat preservation through fermentation. Southern and Central Europe, dating back to Roman times, is the original home of many of these cured and fermented meat products, most made from pork and beef. The name salami is believed to have originated from the city of Salamis in Cyprus, which was destroyed over 2000 years ago (Lücke, 1985). Emigrants carried knowledge of these processes and practices to North America and Australia. These regions now share a range of whole-meat bacon, to be cooked before eating, ready-to-eat country ham, and chopped semi-dry cerevalat, dry German salami and pepperoni, which are smoked, and dry Italian salame and chorizo. Cooked fermented meat products such as mortadello, kochsalami and thüringer are less common (Campbell-Platt, 1987). Salsiccia and soppressata are traditional dry fermented sausages produced in Basilicata in Southern Italy (Parente et al., 2001a). In North America, the Inuits produce milkiyuk from whale and iqunaq from duck (Bacus, 1984). The hotter regions of Africa and Asia are the home of relatively few fermented meat products, 67 although whole-meat dry uncooked jerky is produced in Africa as well as America (Klettner and Baumgartner, 1980; Campbell-Platt, 1987). Some of the common fermented meat products of Thailand are nham (fermented beef or pork sausage), naang (fermented pork or beef) nang-khem (fermented buffalo skin) and sai-krork-prieo (fermented sausage) (Phithakpol et al., 1995). Many traditional meat products of different countries have been well documented and studied such as fermented sausages, salami of Europe (Campbell-Platt and Cook, 1995), ham (Simoncini et al., 2007), alheira of Portugal (Ferreira et al., 2006), androlla of Spain (Garcia Fontán et al., 2007), salsiccia and soppressata of Italy (Parente et al., 2001a), jerky of America (Baruzzi et al., 2006) and Africa (Klettner and Baumgartner, 1980), nham of Thailand (Visessanguan et al., 2006), lup cheong of China (Leistner, 1995). Lactic acid bacteria (LAB) exert an important effect on the production and quality of the various fermented meat products (Schillinger and Lücke, 1987; Hammes and Hertel, 1998). Pediococcus and Lactobacillus are active in producing lactic acid and thus help in lowering of pH, which helps preserve meat (Bacus, 1986). The microflora of fresh raw meat, stored aerobically under refrigeration, largely consists of Gram- positive, and oxidase positive rods, particularly psychrotrophic pseudomonads (McMeekin, 1982), enterobacteriaceae (Gill, 1982) and low numbers (102-103 cfu/g) of LAB (Hammes and Knauf, 1994). During meat 68 fermentation, water activity is reduced and the oxygen present is rapidly consumed, thus pseudomonads, which require oxygen and are sensitive to salt and nitrite are inactivated (Hechelmann et al., 1977). Similarly, enterobacteriaceae is also reduced at low oxygen tension, low pH and in presence of salt (Grau, 1981), which results the rapid growth of LAB (Hammes and Knauf, 1994) and also micrococci (ÿavlek et al., 1971). In fermented meat products, the dominant microorganisms are mostly species of LAB- Lactobacillus, e.g., Lactobacillus sakei, Lactobacillus curvatus and Lactobacillus plantarum; entorococci mainly Enterococcus faecium; Pediococcus pentosaceus, Leuconostoc carnosum, Leuc. gelidium, Leuc. pseudomesenteroides, Weissella, etc. (Collins et al., 1993; Parente et al., 2001a,b); and also coagulase-negative staphylococci (Hugas et al., 2003). Species of Micrococcus and Staphylococcus help reduce nitrate if added, to nitrite in fermented sausages (Lücke, 1985). Staphylococcus aureus is regularly found in meat and fermented sausages (Barber and Deibel, 1972). Raw sausage mixtures may contain considerable numbers of Bacillus spores, of which spices are a major source (Neumayr et al., 1983). Some yeasts and moulds may develop on the surface of dry fermented sausages during ripening (Lücke, 1988; Tamang and Fleet, 2008). Species of yeasts Debaryomyces, Candida, Cryptococcus and Trichosporon have been reported in traditional Greek dry salami (Metaxopoulos et al., 1996). Species of Penicillium constituted the surface mycoflora of chorizo de 69 Cantimpalos, a Spanish variety of fermented sausage (Lǝpez-Díaz et al., 2001). Ability of LAB to inhibit putrefactive, pathogenic and toxinogenic bacteria has been reviewed periodically (Holzapfel et al., 1995; Ouwehand, 1998; Nout, 2001). Bacteriocinogenic enterococci can be used to enhance preservation in meat products (Hugas et al., 2003). During meat fermentation, the microbial growth, the acidification and the proteolysis offer favourable conditions for the production of biogenic amines (Hugas et al., 2003). The production of biogenic amines in fermented meat has been attributed to the action of several microorganisms such as pseudomonads, enterobacteriaceae, enterococci and lactobacilli (Stratton et al., 1991; Halász et al., 1994; Silla-Santos, 1996; Bover-Cid et al., 2001). Dry fermented sausages are worldwide diffused fermented meat products that can be a source of biogenic amines (Suzzi and Gardini, 2003). Excessive consumption of biogenic amines can be a health concern that may lead to a variety of cutaneous, gastrointestinal and neurological symptoms (Taylor, 1986; Suzzi and Gardini, 2003). Sikkim (Fig. A) is the Himalayan state of India with an area of 7096 sq. km and the altitude ranges from 300 m to 8500 m. The state comprises of four districts: North, East, South and West. A total population of Sikkim is 540,493 (Census, 2001) and is populated by three major ethnic groups of people, the Nepali, the Bhutia and the Lepcha. The domestic 70 livestock of Sikkim includes cattle, sheep, goats, pigs, yaks, poultry, etc. which is mainly used for meat, milk and milk products (Balaraman and Golay, 1991). Yaks (Bos grunniens) are reared mostly on extensive alpine and sub alpine scrub lands between 2100 m to 4500 m altitude for milk products and meat (Sharma et al., 2006). Traditional food has always been rich ingredients to the people of the Eastern Himalayas including North East India (Tamang, 2001). About 12.6 % of the total daily food consumed in local diet represents fermented foods (Tamang et al., 2007). The food survey shows that 11.7 % of people in Sikkim are vegetarian and 88.3% are non-vegetarians (Tamang et al., 2007). The Bhutia and the Lepchas usually prefer beef, yak and pork. Beef is taboo to majority of Nepalis except Tamang and Sherpa castes. The Newar caste of Nepalis prefers to eat buffalo meat. The Bhutias and the Lepchas in North Sikkim, slaughter yaks occasionally, consume the fresh meat and the rest is preserved by smoking or drying or fermenting. Varieties of ethnic fermented foods and beverages are indispensable cultural foods of the people of Sikkim Himalayas including different types of meat based products (Tamang, 2005a). 71 J&K N CHINA UTTARKHAND NEPAL U.P. CHINA NORTH NEPAL Mangan CHINA S I K K I M WEST Gangtok Geyzing SOUTH EAST BHUTAN Namchi The Darjeeling Hills Fig A. Map showing the Sikkim Himalaya 72 Kumaun (Fig B), hills of Uttarakhand is situated in the Central Himalaya at the tri-junction of Nepal, Tibet (China) and India, and the region extends from 28°44’ & 30°49’ N latitudes to 78°45’ & 81°5’E longitudes with an area of 21,033 km2 (Nandy et al., 2006). A total population of Uttarakhand is 8479,562 (Census, 2001). Five major tribes, i.e., the Tharus, the Jaunsaries, the Buxas, the Bhutias and the Rajis numbering 179,002 inhabit the Central Himalayan region of Uttarakhand. The Tharus, the Buxas and the Jaunsaries are agriculturists while the Bhutias are pastoralists and the Rajis are mostly hunters and gatherers. The Bhutias, a transhumant community of mongoloid origin, inhabit the high altitude regions of Uttarakhand at Indo-Tibetan & Indo-Nepal borders, a zone of ethnic intermixing and cultural assimilation. They show close racial and cultural affinity to the Tibetans.